GB1572029A

GB1572029A - Assembly for removably attaching flexible cutting line element in grass trimmer

Info

Publication number: GB1572029A
Application number: GB923/78A
Authority: GB
Original assignee: McGraw Edison Co
Current assignee: McGraw Edison Co
Priority date: 1977-01-14
Filing date: 1978-01-10
Publication date: 1980-07-23
Also published as: FR2425195A1; GB1572030A; DE2801847A1; AU518758B2; CA1098721A; FR2439541A1; JPS53107920A; US4118865A; AU3242378A

Description

PATENT SPECIFICATION

( 21) Application No 923/78 ( 22) Filed 10 Jan 1978 ( 31) Convention Application No 759424 ( 32) Filed 14 Jan 1977 in ( 33) ( 44) ( 51) United States of America (US)

Complete Specification Published 23 Jul 1980

INT CL 3 AOIG 3/06 AOID 35/262 ( 52) Index at Acceptance NJ AIF 161 DH ( 54) IMPROVED ASSEMBLY FOR REMOVABLY ATTACHING FLEXIBLE CUTTING LINE ELEMENT IN GRASS TRIMMER ( 71) We McGRAW-EDISON COMPANY a corporation organised and existing under the laws of the State of Delaware United States of America, of 333 West River Road Elgin State of Illinois 60120 United States of America do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be 1 ( O particularly described in and by the following statement:-

This invention relates generally to a trimmer for cutting grass or like vegetation which employs a length of non-metallic e g.

plastics line as the cutting element.

Many different arrangements for attaching a length of cord to a rotatable member in a crass trimmer or edger are shown in the prior art For example, in one embodiment shown in U S Patent 3708 967.

issued January 9 1973 lengths of cutting line are looped through apertures spaced about the periphery of and tied to a rotatable disk In an alternative embodiment of the device radiallv extending apertures communicating with the peripheral apertures are also provided in the disk Lengths of line each having a knotted end are received in the last mentioned apertures.

The knots secure the lines to the disk with the aid of the centrifugal force produced during rotation thereof.

Still another arrangement for attaching short lengths of line to a rotating member in a grass trimmer is shown in U S Patent 3.831 278 issued August 27 1974 wherein a diametrically extending channel is defined in the member An axial recess communicating with the channel is also formed in the member A knot or enlarged hub portion at the center of a length of cutting line is received in the recess with the opposite ends of the line extending radiallv outwardly through opposite ends of the channel In this case the central knot secures the line to the member against the centrifugal force created upon rotation of the member.

Whilst the prior art arrangements described heretofore function satisfactorily for the most part to secure a length of cutting line to the rotating member of a grass edger or tr.nmer they have certain disadvantages which make them undesirable For instance, in the case of the first described embodiment of Specification No 3708967 tying the end of the cutting line to the rotating disk member can be time consuming as a typical nylon or plastic cutting element while being relatively flexible is sufficiently stiff to make it difficult to tie The use of a knotted end on the cutting line to retain the line in position with respect to the rotating member provides no positive means for securing the line during non-use of the trimmer as it requires the centrifugal foce generated by the rotating member to retain the line on the member.

In the case of 3 831278 device, it appears that mounting the cutting line properly on the rotating member could also be difficult and time consuming.

The present invention provides a trimmer for cutting grass of the like vegetation including in combination rotatable drive means and a non-metallic, flexible cutting line element of a predetermined length, having first positive securing means provided thereon and an assembly for removably attaching said length of cutting line element to said rotatable drive means for spinning said cutting line element, said assembly including a hub member coupled to said drive means for rotation thereby, said hub member including second positive securing means provided on the free end thereof, said first and second positive securing means being engageable together to positively retain said cutting line element on said hub member so that said element extends generally radially outwardly therer I tn ( 11) 1 572 029 1 572 029 -from during or in the absence of rotation of said hub member, whereby a positive force is required to disengage said cutting line element from said hub member.

It should be noted that in the prior art arrangements discussed above, the cutting lines illustrated have had circular cross sections The cutting surfaces therefore appear to be somewhat blunt and could thus 1) be less effective against thick or high grass.

In preferred embodiments of this invention a polygonal, e g triangular cross-section line is used to provide a sharper cutting element.

Briefly, a preferred embodiment of the trimmer incorporating a cutting line attachment assembly which comprises a hub member which is driven rotatably by the drive shaft of the trimmer motor The hub member includes a post extending outwardly from the free end, parallel to the axis of rotation thereof, but slightly off center with respect thereto An outer rim portion is also formed on the periphery of the free end of the hub member The rim portion is located on the side of the axis of rotation of the hub member opposite that of the post and partially surrounds the post An aperture is defined in the rim portion which extends radially with respect to the hub member.

A length of cutting line to be attached to the hub member preferably includes an eyelet connector affixed at one end of the line The opposite end of the line may be received in the aperture in the rim portion to extfend radially outwardly therefrom.

The post is then received in the eyelet aperture for securing the first mentioned end of the line to the hub member An off center post provides ease of attachment and remloval of the eyelet connector thereto.

The hub member may also be thickened on the opposite side from the line to provide a counterbalancing weight which minimizes any vibration due to the unbalanced weight of the line The exterior wall of the rim portion is preferably tapered about the aperture to minimize the possibility of shearing the line ( O when the latter engages objects such as stones etc during the use of the trimmer and the interior walls of the rim portion are preferably angled also to provide for ease of insertion of the end of the cutting line into the aperture therein.

A preferred cutting line or cord has a triangular cross section thereby providing a plurality of edges which efficiently slice through grass and the like vegetation.

A preferred embodiment of a trimmer according to the invention will now be described with reference to the accompanying drawings in which:Fiiti'e 1 is a perspective view of a lawn trimmer according to the invention:

Figure 2 is an enlarged fragmentary perspective view of the motor housing of the trimmer of Figure I illustrating the cutting line element and hub member including the line attaching means according to the invention; Figure 3 is an enlarged fragmentary view of the cutting line element and hub member of Figure 2; Figure 4 is a fragmentary view of the cutting line element and hub member of Figure 3 illustrating the manner in which a length of cutting line is attached to the rotating hub member of the trimmer according to the invention; Figure 5 is a perspective view of a length of cutting line according to the invention:

Figure 6 is a cross sectional view of the cutting line of Figure 5 taken along the line 6-6:

Figure 7 is an end view of the hub member of Figure 3 taken along the line 7-7: and Figure 8 is a sectional view of the hub member of Figure 6 taken along the line 8-8.

Referring now to the drawing in greater detail wherein like numerals have been employed throughout the various views to designate similar components there is illustrated in Figure 1 a grass trimmer designated generally by the number 10 The trimmer includes a handle portion 12 to which there is connected a shaft 14 of about three feet in length At the opposite end of the shaft there is provided a motor housing 16 In the embodiment of the trimmer depicted in Figure 1 a high r p m electric AC motor (not shown) is mounted within the housing 16 An electrical cord 18 extends through the handle 12 and shaft 14 of the trimmer into housing 16 whereat it is connected to the motor to provide electrical energy thereto Male plug 19 at the free end of the cord 18 is adapted for connection to a suitable source of electricity A switch (not shown) is provided in handle 12 for operating the motor A trigger type switch actuator 20 is used to operate the switch to control the application of energy to the motor.

The free end 22 of the motor housing includes a flat wall portion 24 defining an aperture 25 (Figure 8) through which the rotatably driven drive shaft 27 of the motor extends.

A hub member 26 to which a relatively short length of cutting line 28 is attachable.

is mounted on the free end of the motor drive shaft for rotation therewith A shroud integrally formed with the housing, partiallv surrounds the hub member and cutting line to control the direction in which grass clippings or other objects engaged by the spinning line 28 are projected.

The hub member 26 is preferably of molded plastic construction and includes a 1 ( O 1 ( 05 1 572 029 central body portion 32 extending outwardly from an enlarged flange portion 36 An axially extending recess 38 (Figure 8) is defined in end 37 opposite free end 34 of the member for receiving the motor drive shaft 27 The hub member is attached to the drive shaft via conventional means, such as for example, a pin An extension portion 40 at end 37 of the hub member extends through the aperture in wall portion 24 of the housing so that surface 42 of the flange portion 36 is positioned adjacent thereto.

The flange portion 36 of the hub member overlies aperture 25 in wall 24 of the housing to prevent grass clippings, etc, from entering the motor housing therethrough.

A rim portion 44 extends outwardly from and partially about the periphery of the free end 34 of the hub member 26 The rim portion defines a radially extending aperture 46 therein The outer wall surface 48 of the rim portion surrounding the aperture 46 is tapered to eliminate sharp edges which could damage the plastic cutting line.

A cylindrically shaped post 50 having a predetermined diameter length extends outwardlv from end 34 of the hub member substantially parallel to the axis of rotation thereof The post 50 is positioned predeterminedlv off center (see Figure 7) with respect to the axis of rotation in the direction opposite the rim portion 44 along an imaginary line extending radially through the aperture 46 and post 50 The purpose of offsetting the post 50 in this manner is to permit more space for the user to attach the eyelet connector thereby making attachmrent and removal of the line relatively simple The post 50 can however, be coincident with the axis of rotation of the hub member if desired Also the hub member is molded to provide an inherent counterbalancing effect for proper rotation upon attachment of cutting line 28 thereto.

This is accomplished by the provision of a thickened portion 51 of the hub member on the side thereof opposite the rim portion 44.

The cutting line 28 according to the invention includes a relatively short (approximatelv three inches) piece of mono or multi-filament nylon or the like material having a looped end 29 In the preferred embodiment, shown best in Figures 5.

looped end 29 is provided by an eyelet connector 31 crimped onto the line end The connector defines a circular aperture 37 having a diameter slightlv larger than the diameter of post 50 Thus, upon receipt of the post 50 in aperture 37 of the connector there is a minimum of play therebetween.

Looped end 29 can be provided in many other wavs which will be understood by one skilled in the art.

The line 28 according to the invention has a triangular cross section (see Figure 6) to provide three edges, such as 33, for slicing through grass or the like vegetation The slicing edges 33 on line 28 provide for more efficient cutting of grass.

The cutting line is quickly and easily attached to the hub member 26 The manner of attachment of the line is illustrated in Figure 4 of the drawing To attach line 28, the free end 35 thereof is inserted from the post side of rim portion 44 through aperture 46 until the aperture 37 in eyelet connector 31 is aligned with post 50 To provide for ease of insertion of the free end 35 of the line into aperture 46 in the rim portion 44.

the interior walls 45, 47 of the rim portion are angled toward the aperture 46 Also a third angled wall portion or ramp 49 is formed at the free end of the hub member adjacent walls 45 47 The angled walls 45.

47 and ramp 49 converge toward the aperture 46 to provide a guide for the free end 35 of the cutting line 28 After the line is fed through the aperture, the eyelet is placed over the post so that the latter is received in aperture 37 (see Figures 3 and 7) The post is sufficiently long, extending outwardly beyond the point of aperture 46 in the rim portion to require that the flexible line be bent to insert post 50 in eyelet aperture 37.

In this fashion once the eyelet connector is mounted on the post 50 is shown in Figures 3 and 7, it cannot inadvertently become detached from the hub member.

The assembly according to the invention thus provides a simple vet effective means for easily and quickly removably attaching a short length of nylon or the like cutting line to a rotatably driven member of a grass trimmer which overcomes the drawbacks of prior art arrangements described heretofore.

While a particular embodiment of the invention has been shown and described, it should be understood that the invention is not limited thereto as many modifications thereof may be made.

The cutting line forming part of the trimmer claimed herein is the subject of our copending application number 9359/79 (Serial No 1572030).

Claims

WHAT WE CLAIM IS:-

1 A trimmer for cutting grass of the like vegetation including in combination, rotatable drive means and a non-metallic, flexible cutting line element of a predetermined length having first positive securing means provided thereon and an assembly for removably attaching said length of cutting line element to said rotatable drive means for spinning said cutting line element, said assembly including a hub member coupled to said drive means for rotation thereby, said hub member including second positive securing means provided on the free end thereof, said first and second positive secur1 572 029 ing means being engageable together to positively retain said cutting line element on said hub member so that said element extends generally radially outwardly therefrom during or in the absence of rotation of said hub member whereby a positive force is required to disengage said cutting line element from said hub member.

2 A trimmer as claimed in claim 1 wherein said first positive securing means includes connector means attached to said cutting line element and wherein said second positive securing means includes means for receiving said connector for positive engagement therewith.

3 A trimmer as claimed in claim I or 2 wherein said hub member further includes rim means spaced from said second positive securing means having a passage formed therein through which the end of said cutting line element opposite said connector means passes radially outwardly from said hub member.

4 A trimmer as claimed in claims 12 or 3 wherein said hub member is generally cylindrical in construction and includes means thereon for counterbalancing said cutting line element.

A trimmer as claimed in claim 4 wherein said counterbalancina means includes an enlarged portion of said hub member on the side thereof opposite said cutting line element.

6 The trimmer of anv one of claims 1 to 5 having rim means extending outwardly from and along at least a portion of the free end of said hub member and being spaced from said second securing means, said rim means defining an aperture extending substantially radially with respect to the axis of rotation of said hub member the end of said length of cutting line opposite first securing means being receivable in said aperture with said last-mentioned end extending radially outwardly from said rim means and said first and second securing means being engageable for removablv attaching said length of cutting line to said hub member.

7 A trimmer as claimed in anv one of claims I to 6 wherein the said first securing means comprises a loop formed at one end of said length of line said second securing means comprises a post member formed at the free end of said hub member in spaced relation to said rim means, and wherein said post member is receivable in said loop for removably attaching said length of cutting line to said hub member.

8 A trimmer as claimed in claim 7 wherein said loop means includes an evelet connector having an aperture of a predetermined shape defined therein said connector being affixed to one end of said cutting line.

and wherein said post is shaped complementarily to the shape of said aperture in said connector but dimensionally slightly smaller than said aperture whereby upon receipt of said post in said aperture there is a small amount of play between said connector and said post.

9 A trimmer as claimed in anv one of claims 1 to 8 wherein said cutting line has a polygonal cross section thereby to provide a plurality of cutting edges extending the length thereof.

A grass trimmer as claimed in any one of claims 1 to 9 wherein said cutting line has a triangular cross section thereby to provide three grass cutting edges extending the length thereof.

11 A grass trimmer as claimed in any one of claims 1 to 10 wherein the rotatable drive means includes a housing having motor means mounted thereon said motor means including rotatable drive shaft means said housing having a wall portion defining an aperture through which said drive shaft means extends and wherein said rotatably driven hub member is coupled to said drive shaft means at one end thereof for rotation therewith said hub member including a flange portion formed at said one end and positioned in spaced relation with respect to said wall portion outside of said housing said flange portion being sufficiently large to cover said aperture thereby to prevent grass and the like from entering said housing through said aperture.

12 A grass trimmer as claimed in anv one of claims 1 to 11 wherein said rotatablv driven member includes guide means for guiding said end of said cutting line opposite said loop means into the aperture in said rim means said guide means including angled walls formed on said rim means adjacent said aperture and a ramp portion formed on said member, all of which converge toward said aperture in said rim means.

13 A grass trimmer as claimed in any one of claims 3 to 12 wherein said rim means extends about a portion of the periphery of said hub member and wherein the free end of said post extends outwardly bevond the point at which the radially extending aperture in said rim means is defined wherebv the cutting line must be bent to insert said post into the aperture defined by said connector said rotatablv driven member is of a molded plastic construction with said post said rim means and said flange portion being formed integrally therewith.

14 A trimmer as claimed in anv one of the preceding claims wherein a positive force is required to disengage the first position securing means for the second position securing means.

A trimmer as claimed in claim 1 substantially as hereinbefore described with reference to and as illustrated in any one of Figures 1 2-4 7 and 8.

1 ()0 1 S 1 572 029 5 McGRAW-EDISON COMPANY, Per: BOULT, WADE & TENNANT, 34 Cursitor Street, i London, EC 4 A 1 PO.

Chartered Patent Agents.

Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey, 1980.

Published by The Patent Office 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.